The present invention relates to a safety device used in case a vehicle rolls over, and in particular to such a safety device that comprises:                at least two curved bars, each curved bar having a first end and a second end, said bars being movable from a retracted position to a deployed position in case of a rollover;        a pre-stressed system for deploying each bar;        a trigger system that is activated in case the vehicle rolls over; and        at least one locking member that maintains the pre-stress and that is released by means of the trigger system, thereby releasing each bar from its retracted position;        
Such devices are known, for example, from Documents U.S. Pat. No. 5,205,585 and WO-A-91/02669.
In those documents, the systems for pre-stressing, locking, and controlling the curved roll-bars are disposed behind the backs of the seats to be protected so that those systems encroach on the length of the luggage compartment over substantially the entire height of said compartment.